Del Potro, the 2009 US Open champion, overcame 16 aces by Querrey, who was seeded fourth.

On Saturday, del Potro will take on No. 1-seeded Milos Raonic for a berth in the final. Raonic edged Kyle Edmund 4-6, 6-3, 6-4.

Raonic and del Potro are two of the biggest hitters on tour and have split two past matches against each other — but they have not faced off since 2013.

On the other half of the draw, Jack Sock moved into the semifinals by beating Steve Johnson 6-4, 7-6 (4) in an all-American matchup.

Sock will play yet another American next: Donald Young, who didn’t even need to play a point to get to the semifinals. Young’s quarterfinal opponent, Steve Darcis, withdrew from the tournament, citing personal reasons.

The third-seeded Sock is the only player remaining in the hard-court event who has not dropped a set as he seeks his second title of 2017, third of his career. Young has never won an ATP title. Sock is 2-0 against Young.